Leg stiffness is an important performance determinant in several sporting activities. This study evaluated the criterion-related validity and reliability of 2 field-based leg stiffness devices, Optojump Next® (Optojump) and Myotest Pro® (Myotest) in different testing approaches. Thirty-four males performed, on 2 separate sessions, 3 trials of 7 maximal hops, synchronously recorded from a force platform (FP), Optojump and Myotest. Validity (Pearson’s correlation coefficient, r; relative mean bias; 95% limits of agreement, 95%LoA) and reliability (coefficient of variation, CV; intraclass correlation coefficient, ICC; standard error of measurement, SEM) were calculated for first attempt, maximal attempt, and average across 3 trials. For all 3 methods, Optojump correlated highly to the FP (range r = .98–.99) with small bias (range 0.91–0.92, 95%LoA 0.86–0.98). Myotest demonstrated high correlation to FP (range r = .81–.86) with larger bias (range 1.92–1.93, 95%LoA 1.63–2.23). Optojump yielded a low CV (range 5.9% to 6.8%), high ICC (range 0.82–0.86), and SEM ranging 1.8–2.1 kN/m. Myotest had a larger CV (range 8.9% to 13.0%), moderate ICC (range 0.64–0.79), and SEM ranging from 6.3 to 8.9 kN/m. The findings present important information for these devices and support the use of a time-efficient single trial to assess leg stiffness in the field.
Luca Ruggiero, Susan Dewhurst, and Theodoros M. Bampouras
Susan Dewhurst, Leslie Peacock, and Theodoros M. Bampouras
Physical activity assists older individuals’ functional ability and postural stability. Recently, Scottish country dance (SCD) was reported as being a beneficial form of physical activity for functional ability in older females. This study aims to examine the effect of SCD on postural stability. Scottish country dancers (n = 20) were compared with physically active controls (n = 33) for static postural sway measured on a force platform. The Romberg and Tandem stances were used under ‘eyes open’ and ‘eyes closed’ conditions. Ninety-five percent ellipse area and sway velocity were calculated from the center of pressure displacement. Ninety-five percent ellipse area was the same for both groups in all tests. The control group had greater sway velocity for all tests (P < .01) except Tandem eyes closed. SCD participation resulted in similar postural sway as participation in other physical activities, however nondancers may need a greater amount of regulatory activity to maintain balance.
Susan Dewhurst, Norah Nelson, Paul K. Dougall, and Theodoros M. Bampouras
The effects of long-term participation in Scottish country dance on body composition, functional ability, and balance in healthy older females were examined. Participants were grouped into dancers and physically active nondancers (ages 60–70 and 70–80 for both groups). Physical activity, body composition (body-mass index, skinfold thickness, waist-to-hip ratio), functional ability (6-min walk distance, 6-m walk time, 8-ft up-and-go time, lower body flexibility, shoulder flexibility), and static balance were measured. Younger dancers and physically active nondancers had similar 6-min walk distance, 6-m walk time, and 8-ft up-and-go time results; however, while older dancers performed similarly to younger dancers, older physically active nondancers performed poorer than their younger counterparts (p < .05). Body composition and static balance were the same for all groups. Regular physical activity can maintain body composition and postural stability with advancing age; however, Scottish country dance can delay the effects of aging on locomotion-related functional abilities.
Louis Howe, Jamie S. North, Mark Waldron, and Theodoros M. Bampouras
Context: Ankle dorsiflexion range of motion (DF ROM) has been associated with a number of kinematic and kinetic variables associated with landing performance that increase injury risk. However, whether exercise-induced fatigue exacerbates compensatory strategies has not yet been established. Objectives: (1) Explore differences in landing performance between individuals with restricted and normal ankle DF ROM and (2) identify the effect of fatigue on compensations in landing strategies for individuals with restricted and normal ankle DF ROM. Design: Cross-sectional. Setting: University research laboratory. Patients or Other Participants: Twelve recreational athletes with restricted ankle DF ROM (restricted group) and 12 recreational athletes with normal ankle DF ROM (normal group). Main Outcome Measure(s): The participants performed 5 bilateral drop-landings, before and following a fatiguing protocol. Normalized peak vertical ground reaction force, time to peak vertical ground reaction force, and loading rate were calculated, alongside sagittal plane initial contact angles, peak angles, and joint displacement for the ankle, knee, and hip. Frontal plane projection angles were also calculated. Results: At the baseline, the restricted group landed with significantly less knee flexion (P = .005, effect size [ES] = 1.27) at initial contact and reduced peak ankle dorsiflexion (P < .001, ES = 1.67), knee flexion (P < .001, ES = 2.18), and hip-flexion (P = .033, ES = 0.93) angles. Sagittal plane joint displacement was also significantly less for the restricted group for the ankle (P < .001, ES = 1.78), knee (P < .001, ES = 1.78), and hip (P = .028, ES = 0.96) joints. Conclusions: These findings suggest that individuals with restricted ankle DF ROM should adopt different landing strategies than those with normal ankle DF ROM. This is exacerbated when fatigued, although the functional consequences of fatigue on landing mechanics in individuals with ankle DF ROM restriction are unclear.